Distributed coherent radar high-speed target signal accumulation and BSSL suppression method

Abstract

The invention discloses a distributed coherent radar high-speed target signal accumulation and BSSL suppression method, which is applied to the field of radar signal processing and aims at solving the problems of RM and DFM in the signal accumulation process of high-speed target echoes and the caused BSSL phenomenon. The invention provides a multi-stage processing architecture integrating in-channel accumulation, BSSL suppression and inter-channel accumulation. The method comprises the following steps: firstly, constructing an analytical expression of BSSL, and deeply analyzing distribution characteristics of the analytical expression and a coupling relationship between the analytical expression and system parameters such as carrier frequency; secondly, designing a group of optimized multi-carrier frequency parameters, so that BSSL distribution areas corresponding to different carrier frequencies are not overlapped with each other; and then, multi-pulse accumulation in the channel is realized by using the corrected GRFT, and a BSSL suppression method based on a minimization strategy is provided, and BSSL is effectively suppressed by performing in-channel comparison among different carrier frequency echo data. And finally, after BSSL suppression is completed, inter-channel accumulation is executed, and high-efficiency accumulation of high-speed weak target echoes is realized. The method is suitable for distributed coherent radar signal accumulation and BSSL suppression.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of radar signal processing, and particularly relates to a channel-in and channel-between accumulation processing technology for high-speed targets. BACKGROUND

[0002] In recent years, with the development of aerospace technology, high-speed weak targets represented by near-space vehicles and stealth aircraft have emerged. Such targets usually have high relative motion speed and low RCS (Radar Cross Section), resulting in weak echo energy and difficulty in accurate detection by conventional radar systems. As a new radar operating mode, distributed coherent radar can effectively improve the detection capability of high-speed weak targets by transmitting orthogonal waveforms and performing coherent accumulation on echo signals, and utilizing multi-pulse-multi-channel data fusion.

[0003] However, the following key challenges still exist in the actual signal accumulation process: (1) In a long CPI (Coherent Processing Interval), due to the high-speed relative motion between the target and the radar, obvious RM (Range Migration) and DFM (Doppler Frequency Migration) phenomena will appear in the target echo signal, which will significantly affect the performance of traditional accumulation methods; (2) Due to the differences in the topological structure between the nodes of the distributed MIMO radar, the envelope amplitude and phase of the echoes are inconsistent after the channel-in accumulation of different TRPs (Transmit-Receive Pair), and further envelope alignment and phase compensation are needed to realize effective channel-between accumulation; (3) When RFT (Radon-Fourier Transform) type methods are used for accumulation of high-speed target signals, BSSL (Blind Speed Sidelobe) phenomenon is easily produced, which will further cause false alarm or target mis-detection.

[0004] To solve the above problems, a large number of researches have focused on channel-in and channel-between accumulation processing of high-speed targets in recent years. For example, the GRFT (Generalized Radon-Fourier Transform) algorithm proposed by J. Xu et al. and the channel-between accumulation method proposed by M. Wang et al. have improved the accumulation performance to some extent. However, the method of M. Wang et al. does not fully consider the false alarm problem caused by BSSL phenomenon, which may affect the subsequent data processing effect. SUMMARY

[0005] The present application aims at overcoming the deficiencies in the prior art, and provides a distributed coherent radar high-speed target signal accumulation and BSSL suppression method.

[0006] The technical scheme adopted by the present application is as follows: a distributed coherent radar high-speed target signal accumulation and BSSL suppression method, comprising:

[0007] A1, design a set of feasible carrier frequency parameter solutions based on constraint propagation, so that the BSSL between different node carrier frequencies forms a non-overlapping distribution;

[0008] A2, use the set of feasible carrier frequency parameter solutions in step A1 as the carrier frequencies of each distributed node, and each distributed node transmits a detection signal at the same time;

[0009] A3, obtain the detection mixed echo of each distributed node pulse radar;

[0010] A4, after down-converting the detection mixed echo, use a set of matched filters to perform matched separation filtering on the mixed signal;

[0011] A5, perform modified GRFT processing on the echo signal after matched separation filtering to obtain the coherent accumulation result of the intra-channel GRFT signal;

[0012] A6, according to the geometric relationship of the system, formulate a BSSL suppression pair selection strategy and divide the suppression pairs, and perform a minimum suppression operation;

[0013] A7, construct an inter-channel envelope shift function to perform inter-channel signal accumulation;

[0014] A8, perform constant false alarm detection processing according to the inter-channel accumulation result of step S8, and the accumulation result does not contain BSSL, so as to obtain accurate detection results of the number and position of targets.

[0015] The beneficial effects of the present application: the present application proposes a multi-stage processing architecture that fuses intra-channel accumulation, BSSL suppression and inter-channel accumulation; first, the analytical expression of BSSL is constructed, and the distribution characteristics and the coupling relationship between the distribution characteristics and the system parameters such as carrier frequency are analyzed in depth; second, a set of optimized multi-carrier frequency parameters are designed, so that the BSSL distribution regions corresponding to different carrier frequencies do not overlap with each other; then, a BSSL suppression method based on the minimum strategy is proposed, which effectively suppresses BSSL by comparing the echo data at different carrier frequencies within the channel; finally, after the BSSL suppression is completed, inter-channel accumulation is performed to realize efficient accumulation of high-speed weak target echoes; the present application can be applied to distributed coherent radar signal accumulation and BSSL suppression. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flowchart of the present application.

[0017] Figure 2 The feasibility analysis result of the carrier frequency matrix.

[0018] Figure 3 The intra-channel accumulation result based on GRFT;

[0019] Wherein, (a) is the intra-channel accumulation result of channel G 11 , (b) is the intra-channel accumulation result of channel G 22 , it can be clearly seen that the relative speed difference between BSSL and target is different, which proves the correctness of the theory.

[0020] Figure 4 The inter-channel accumulation and BSSL suppression result;

[0021] Wherein, (a) is the accumulation and suppression result of the method proposed in the present application, (b) is the accumulation and suppression result based on the complementary window function method, and (c) is the accumulation and suppression result of the improved minimum window GRFT method. DETAILED DESCRIPTION

[0022] In order to facilitate those skilled in the art to understand the technical content of the present application, the content of the present application is further explained below in combination with the drawings.

[0023] In this example, the correctness and effectiveness of the present application are verified by Matlab simulation experiment.

[0024] As shown in Figure 1 , the present application provides a distributed coherent radar node carrier frequency design method, which comprises:

[0025] S1, according to the output form of GRFT, when the GRFT is implemented to accumulate in the channel of the uniform acceleration target, the accumulation output contains three parts, which are the main lobe I0 representing the real target, and two types of BSSLI1 and I2 caused by the blind speed, and their distributions can be approximately written as the form of three-dimensional independent distribution multiplied by the distance dimension, the speed dimension and the acceleration dimension, and the expressions are

[0026]

[0027] Wherein, A is the target main lobe amplitude, A p1 is the first type of BSSL amplitude peak, A p2 is the second type of BSSL amplitude peak. rect(·) is a rectangular window function, and

[0028]

[0029] r represents distance, v represents speed, a represents acceleration, r target is the equivalent distance of the transceiver pair observing the target, v target is the equivalent speed of the transceiver pair observing the target, a target is the equivalent acceleration of the transceiver pair observing the target, ρ r =c / 2B is the pulse radar distance resolution, B is the radar bandwidth, λ=c / f c is the signal wavelength, c is the speed of light, f c is the radar carrier frequency. v b =λ / 2T r is the pulse radar blind speed, T r is the pulse repetition interval, T is the coherent accumulation time, r c (p)=r target +pv b T is the first type of BSSL distribution distance dimension center position with the speed ambiguity p; r c (q)=r target +qv b T is the second type of BSSL distribution center position with the speed ambiguity q, δ(·) is an impulse function, p is the first type of BSSL ambiguity, q is the second type of BSSL ambiguity, and

[0030]

[0031] Wherein, v min is the minimum search speed when the GRFT is searched in the channel, v max is the maximum search speed when the GRFT is searched in the channel, ∪ is a union symbol, is an integer set.

[0032] Since the BSSLs in distance, velocity and acceleration dimensions are non-overlapped in any dimension, the output results of the inner product accumulation of the two non-overlapped transceiving pairs are taken as small, so that only the real target exists in the two, and the velocity dimension distribution of the BSSL is simple, and the center and the distribution position are related to the wavelength, i.e. the radar carrier frequency.

[0033] Optionally, the two types of BSSLs are simply written as

[0034]

[0035]

[0036] Wherein, f(r, a) is a complex amplitude determined by distance and acceleration.

[0037] S2, select an OFDM-LFM (Orthogonal Frequency Division Multiplexing-Linear Frequency Modulation) signal as a baseband signal, which is represented as

[0038]

[0039] Wherein, E is the energy of the transmitted signal, and correspondingly, the transmitted signal of the i-th distributed radar node is

[0040] s i (t)=u i (t)exp(j2πf c t)

[0041] Wherein, is the signal amplitude, T p is the pulse width, μ=B / T p is the LFM frequency modulation slope, B is the linear frequency modulation bandwidth, f c is the common carrier frequency, △f is the OFDM sub-band step frequency, and the carrier frequency of the i-th node is f c,i =f c +(i-1)△f. By using the frequency division characteristics of the OFDM-LFM signal, a set of feasible carrier frequency parameter solutions is designed based on constraint propagation, so that the BSSLs between different nodes form non-overlapping distributions. Considering using an optimization model with constraints to determine the carrier frequency values, the optimization function is the sum of the velocity dimension overlapping lengths of the two types of BSSLs between different carrier frequencies, and the optimization goal is to make the velocity dimension overlapping length of the BSSL be 0.

[0042]

[0043] 2(B+(N-1)△f)≤f s

[0044] Where N is the number of distributed nodes, f=[f c,1 ,f c,2 ,…,f c,N ] is the node carrier frequency vector in ascending order, f c,min and f c,max is the minimum and maximum carrier frequency of the system, λ i =c / f c,i is the wavelength of node i, v bi =λ i / 2T r is the equivalent carrier frequency f of node i c,i The corresponding blind velocity, f p =1 / T r is the pulse repetition frequency, △v is the radar velocity resolution, (·)∧(·) represents the overlapping length of the two distributions. This optimization function ensures that the BSSL velocity term distribution in the discrete system is not in the same velocity unit; K is an arbitrary positive integer, is a set of positive integers, f s is the radar system sampling rate.

[0045] Solve the optimization function to obtain the feasible result of the node carrier frequency vector. The specific implementation method is:

[0046] 1) Solve the carrier frequency value matrix used to determine whether the non-overlapping distribution is satisfied

[0047] Based on the idea of ​​constraint propagation, we can transform the N-dimensional search space and constraints of the decision vector f into the first element f in f c,1 And the two-dimensional search space of the step frequency △f is used to achieve the purpose of reducing the range of variable values.

[0048] In the continuous closed interval [f c,min ,f c,max ], with △f c Divide the carrier frequency search interval into discrete units and we can get f c,1 Search value range

[0049]

[0050] Among them, σ is the carrier frequency search index, where, is a rounded-down function. Correspondingly, according to the constraints, the pulse repetition frequency f p is the step frequency search interval, and the corresponding step frequency range is written out

[0051]

[0052] The maximum index of the stepped frequency for each δ is

[0053]

[0054] wherein is the minimum value of the stepped frequency, is the ceiling function.

[0055] According to the range of the carrier frequency values, a one-dimensional carrier frequency value vector can be obtained Secondly, according to each determined carrier frequency a one-dimensional stepped frequency vector satisfying the constraint condition can be obtained Therefore, the two one-dimensional vectors can be written as a two-dimensional carrier frequency value matrix A set of carrier frequencies f can be uniquely determined.

[0056] 2) Search each element in the carrier frequency value matrix, calculate the speed dimension overlap length and select a feasible solution

[0057] Search the two-dimensional carrier frequency value matrix stored in search 1) Each element can determine a set of carrier frequencies f, and the speed dimension overlap length of the set of carrier frequencies is calculated by using the optimization function. If the BSSL distribution exists overlap, the element in the matrix is abandoned and marked as infeasible; if the BSSL distribution satisfies the non-overlapping distribution of each carrier frequency, it is marked as a feasible solution. After the feasibility of all elements is judged, the process is terminated, and one element is selected from the feasible solution as the distributed node carrier frequency vector.

[0058] As shown in Fig. Figure 2 , in the search range, multiple sets of parameter feasible solutions (parameter combinations with an amplitude of 1) are found, and these parameter combinations are equivalent in the signal accumulation effect of BSSL suppression. According to the actual demand, any feasible solution can be selected.

[0059] 3) Select any feasible solution, which corresponds to a common carrier frequency f c,1 and a stepped frequency Δf, determine the carrier frequency vector [f1, f2, …, f N ] as the node transmission carrier frequency, wherein f1=f c,1 , f i -f i-1 =△f,

[0060] S3, taking the selected carrier frequency vector as the carrier frequency of each node, each node transmits a detection signal at the same time.

[0061] S4, obtain the mixed echo of the detection signal from the N distributed nodes from the j=1, 2, …, N distributed node pulse radars

[0062]

[0063] where t denotes the single-pulse fast time, t m = (m-1)T r , m = 1, 2, …, M is the slow time corresponding to the pulse in one coherent integration time, M is the total number of pulses, is the echo signal received by the jth node from the ith node, β is the channel propagation coefficient, which is irrelevant to the main content of the application, so the channel propagation coefficients of different transceiver pairs are taken as the same value, is the target equivalent observation motion equation of the signal receiving node, r ij is the two-way observation equivalent initial distance, v ij is the two-way observation equivalent initial velocity, a ij is the two-way observation equivalent initial acceleration.

[0064] S5, the mixed echo signal received by each distributed node is down-converted, and then a set of matched filters is used for matched separation filtering of the down-converted signals of each node. The ith matched filter is The superscript * indicates taking the conjugate, let r = ct / 2, and the matched filter output signal received by radar j from radar i is

[0065]

[0066] S6, to solve the RW and DFM problems of high-speed targets, the separated echo signal y ij (r, t m ) is corrected by GRFT processing to obtain the coherent integration results of the in-channel GRFT signals as shown in Figure 3 .

[0067] First, the target motion parameter (distance, velocity and acceleration) search range [r min , r max ], [v min , v max ], [a min , a max ] is determined, r min is the minimum distance to be searched, r max is the maximum distance to be searched; v min is the minimum velocity to be searched, v max is the maximum velocity to be searched; a min is the minimum acceleration to be searched, a max is the maximum acceleration to be searched.

[0068] r s (η) = r min+ η△r,η = 1,2,…,N r ,

[0069] v s (κ) = v min + κ△v,κ = 1,2,…,N v ,

[0070] a s (ζ) = a min + ζ△a,ζ = 1,2,…,N a

[0071] where△r,△v,△a are discrete distance, velocity, acceleration search intervals, N r ,N v ,N a are the maximum search indices of discrete distance, velocity, acceleration, with r max = N r △r, v max = N v △v, a max = N a △a, r s ,v s ,a s are N s , N s , and N s dimensional vectors formed by distance search values r r (η), velocity search values v v (κ), and acceleration search values a a (ζ), respectively.

[0072] The matched filtered separated multi-path pulse pressure signals are accumulated in the channel, the process is represented as

[0073]

[0074] η = 1,…N r ,κ = 1,…N v ,ζ = 1,…N a

[0075] where H r,v,a (t m ) is the inter-pulse phase compensation function

[0076]

[0077] The GRFT coherent accumulation output signal of the transceiver pair ij channel is obtained as

[0078]

[0079] where I 0,ijfor the target mainlobe, for the first type of BSSL set, for the second type of BSSL set, which is specifically

[0080]

[0081] wherein, for the two-way observed target equivalent motion parameters, f(r s (η),a s (ζ)) is the complex amplitude determined by the distance and acceleration.

[0082] S7, according to the system geometry, formulate the BSSL suppression pair selection strategy and divide the suppression pairs, and take the smaller BSSL, the specific implementation method is:

[0083] Since the two-way observed target equivalent motion parameters have r ij =r ji ,v ij =v ji ,a ij =a ji , in the channel accumulation output of the transmit-receive pair ij and its symmetric transmit-receive pair ji (i≠j), the target mainlobe I 0,ij is in the same position as I 0,ji , but the BSSL distribution (only considering the velocity dimension) is different, so for G ij which has a symmetric channel, select its symmetric channel G ji as the BSSL suppression pair of channel G ij to take the smaller operation, that is,

[0084]

[0085] Since the BSSL distribution formed by the carrier frequencies f i and f j does not overlap, the output obtained by taking the smaller one only contains the target mainlobe.

[0086] For the accumulation result without a symmetric channel, such as G ii , select a channel G jj which is also without a symmetric channel, to construct the envelope shift function

[0087]

[0088] Through , the target mainlobe of the channel accumulation output G jj and G ii can be aligned to the same position and the BSSL distribution does not overlap, at this time, use

[0089]

[0090] That is, the in-channel accumulation output containing only the target main lobe is obtained.

[0091] S8, constructing an inter-channel envelope shift function, and performing inter-channel signal accumulation. The specific implementation method is:

[0092] After completing the BSSL suppression in step S7, only the target main lobe I 0,ij exists in the in-channel accumulation result of the transceiver pair ij. Optionally, the peak three-dimensional coordinates in the channel are selected, and a positioning algorithm such as the Newton-Raphson method (the method is not unique and is not within the scope of claims in this specification) is used to estimate the position parameters of the target in the three-dimensional Cartesian coordinate system. velocity parameters acceleration parameters At the same time, the position parameters of the node radar are known, and the position parameters of the i-th radar node are set as p i = [x i , y i , z i ], the velocity parameters are set as v i = [v xi , v yi , v zi ], and the acceleration parameters are set as a i = [a xi , a yi , a zi ].

[0093] According to the equivalent motion parameter calculation formula

[0094]

[0095] The double-way observation equivalent initial distance, velocity, and acceleration estimation values can be obtained.

[0096] Optionally, a channel G nn is randomly selected as the inter-channel accumulation reference channel.

[0097] Because there is an envelope difference

[0098] △r nn,ij = r s (η nn )- r s (η ij ),

[0099] △v nn,ij = v s (κ nn )- v s (κ ij ),

[0100] △a nn,ij =a s (ζ nn )-a s (ζ ij )

[0101] Optionally, the selected channel G nn As the inter-channel accumulation reference channel, the inter-channel accumulation can be completed

[0102]

[0103] wherein, is the envelope shift function constructed, and the expressions are respectively

[0104]

[0105] According to the formula, the target signal energy distributed in different channels is focused in the inter-channel coherent accumulation output, and the output result does not contain BSSL, avoiding the false detection caused by BSSL.

[0106] S9, according to the inter-channel accumulation result of step S8, a constant false alarm detection processing is performed, the accumulation result does not contain BSSL, so as to obtain an accurate detection result of the target number and position.

[0107] In the embodiment, the system parameter setting adopted is: the frequency modulation bandwidth B = 1 MHz, the pulse repetition frequency f p = 512 Hz, the pulse number M = 256, the pulse width is 40 μs, the radio frequency band is L band, the maximum sampling frequency is 60 MHz, the selected feasible solution is f c = 1 GHz, △f = 12 MHz, the number of distributed node radars is 3, the equivalent distance of the target relative to radars 1, 2 and 3 is r1 = 10 km, r2 = 10.25 km and r3 = 10.5 km; the equivalent velocity of the target relative to radars 1, 2 and 3 is v1 = 100 m / s, v2 = 116 m / s and v3 = 92 m / s; the equivalent acceleration of the target relative to radars 1, 2 and 3 is a1 = -16 m / s 2 , a2 = -10 m / s 2 and a3 = -8 m / s 2 .

[0108] From Figure 4 it can be clearly seen that compared with the complementary window function method and the improved minimum window GRFT method, the method proposed in the application has higher signal accumulation gain, and can more effectively suppress BSSL, and there is no obvious BSSL in the accumulation plane.

[0109] Those skilled in the art will appreciate that the embodiments described herein are presented for purposes of illustration and understanding of the principles of the application and should not be construed as limiting the scope of the application to such specifically enumerated embodiments. Various modifications and changes can be made to the application by those skilled in the art which will be apparent from this disclosure without departing from the spirit and principles of the application. Any modifications, equivalent substitutions, improvements, etc. made to the application should be included within the scope of the application as defined in the following claims.

Claims

1. A distributed coherent radar high-speed target signal accumulation and BSSL suppression method, characterized in that: include: A1. Design a set of feasible carrier frequency parameter solutions based on constrained propagation, so that the BSSLs between carrier frequencies at different nodes form a non-overlapping distribution; A2. Using the set of feasible carrier frequency parameter solutions in step A1 as the carrier frequency of each distributed node, each distributed node simultaneously transmits a detection signal; A3. Obtaining detection mixed echoes from pulse radars of each distributed node; A4. After down-converting the detection mixed echo, a set of matched filters is used to perform matched separation filtering on the mixed signal; A5. Perform modified GRFT processing on the echo signal after matched separation filtering to obtain the coherent accumulation result of the GRFT signal within the channel; A6. Based on the system geometry, formulate a BSSL suppression pair selection strategy and divide the suppression pairs to perform the minimum suppression operation; A7. Construct an inter-channel envelope shift function to accumulate inter-channel signals; A8. Perform constant false alarm detection based on the inter-channel accumulation results of step S8. The accumulation results do not include BSSL to obtain accurate detection results of the number and position of targets.

2. The distributed coherent radar high-speed target signal accumulation and BSSL suppression method according to claim 1 is characterized in that: Step A1 specifically includes the following sub-steps: A11. According to the GRFT output form, when GRFT is accumulated in the channel to achieve uniform acceleration, the accumulated output contains three parts: the main lobe I0 representing the real target, the first type BSSLI1 and the second type BSSLI2; A12. Determine the carrier frequency value based on a constrained optimization model. The optimization function adopted by the optimization model is the sum of the velocity dimension overlap lengths of two types of BSSLs between different carrier frequencies. The optimization goal of the optimization model is to make the velocity dimension overlap length of BSSL zero.

3. The distributed coherent radar high-speed target signal accumulation and BSSL suppression method according to claim 2 is characterized in that: The constrained optimization model in step A12 is expressed as: 2(B+(N-1)△f)≤f s Among them, f c,i is the carrier frequency of the i-th node, N is the number of distributed nodes, f is the node carrier frequency vector, f c,min and f c,max is the minimum and maximum carrier frequency of the system, λ i is the wavelength of the i-th transmitting node, v bi is the blind rate of the i-th transmitting node, ρ r is the radar range resolution, △v is the radar velocity resolution, △f is the OFDM sub-band step frequency, and B is the linear frequency modulation bandwidth.

4. The method for high-speed target signal accumulation and BSSL suppression of a distributed coherent radar according to claim 3, characterized in that: The solution process of the constrained optimization model in step A12 is: Convert the N-dimensional search space and constraints of the decision vector f into the first element f in f c,1 and the two-dimensional search space of the step frequency △f; According to the carrier frequency value range, we first get the one-dimensional carrier frequency value vector Secondly, according to each determined carrier frequency Find the one-dimensional step frequency vector that satisfies the constraints Write the two one-dimensional vectors into a two-dimensional carrier frequency value matrix Searching for a two-dimensional matrix of carrier frequency values Each element in the matrix can determine a group of carrier frequencies f. The optimization function is used to calculate the BSSL velocity dimension overlap length of this group of carrier frequencies. If there is overlap in the BSSL distribution, the element in the matrix is ​​discarded and marked as infeasible. If the BSSL velocity dimension between the carrier frequencies satisfies the non-overlapping distribution, it is marked as a feasible solution. The feasibility judgment is terminated after all elements are completed, and an element is arbitrarily selected from the feasible solution as the distributed node carrier frequency vector.

5. The method for high-speed target signal accumulation and BSSL suppression of a distributed coherent radar according to claim 4, characterized in that: The implementation process of step A6 is as follows: Since the equivalent motion parameter of the two-way observation target is r ij =r ji ,v ij =v ji ,a ij =a ji , so in the channel accumulation output of the transmit-receive pair ij channel and its symmetrical transmit-receive pair ji channel, the target main lobe I 0,ij with I 0,ji At the same position, but with different BSSL velocity distribution, so for G with symmetric channel ij For example, select its symmetric channel G ji As channel G ij The BSSL suppression performs the minimum operation on i≠j; For the accumulation results without symmetric channels, such as G ii , then select channel G which also does not have a symmetric channel jj , construct the envelope shift function pass Convolution channel G jj The channel accumulation output is G jj With G ii The target main lobes are aligned to the same position and the BSSL distributions do not overlap, and the in-channel accumulation output containing only the target main lobe is obtained.

6. The distributed coherent radar high-speed target signal accumulation and BSSL suppression method according to claim 5, characterized in that: The implementation process of step A7 is as follows: Select the three-dimensional coordinates of the peak value in the accumulated output of the channel containing only the target main lobe of all channels, and use the positioning algorithm to estimate the position parameters, velocity parameters, and acceleration parameters of the target in the three-dimensional Cartesian space coordinate system. At the same time, the position parameters of the node radar are known; According to the calculation formula of equivalent motion parameters, the estimated value of the equivalent initial distance of two-way observation is obtained; Select the reference channel; Calculate the envelope difference of the target main lobe in the channel accumulation output between the reference channel and other channels, and construct an envelope shift function based on the envelope difference; Based on building envelope shift function, the inter-channel accumulation is completed.

7. The method for high-speed target signal accumulation and BSSL suppression of a distributed coherent radar according to claim 6, characterized in that: In step A2, each distributed node simultaneously transmits a detection signal which is an OFDM-LFM signal.

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